first blood bag constituting the blood bag system (12) (10) is formed into a bag shape in soft materials comprising a housing capable bag body the first blood (80). Bag body (80) has a first housing portion which the blood inflow portion (82) is provided with (84), a second housing portion which blood outflow portion (94) is provided with (92), the bag body (80) communicating the inner first housing part (84) and the first housing portion is constituted by partition walls (86, 88) for partitioning the second housing section (92) (84) and the second housing portion (92) communicating with and a passage (90).血液バッグシステム(12)を構成する初流血バッグ(10)は、軟質な材料で袋状に形成されて初流血を収容可能なバッグ本体(80)を備える。バッグ本体(80)は、血液流入部(82)が設けられた第1収容部(84)と、血液流出部(94)が設けられた第2収容部(92)と、バッグ本体(80)内を第1収容部(84)と第2収容部(92)とに仕切る隔壁(86、88)によって構成されて第1収容部(84)と第2収容部(92)とを連通する連通路(90)とを有する。
